A Power Side-Channel Attack on the CCA2-Secure HQC KEM

Thomas Schamberger, Julian Renner, Georg Sigl, Antonia Wachter-Zeh

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

11 Scopus citations


The Hamming Quasi-Cyclic (HQC) proposal is a promising candidate in the second round of the NIST Post-Quantum Cryptography Standardization project. It features small public key sizes, precise estimation of its decryption failure rates and contrary to most of the code-based systems, its security does not rely on hiding the structure of an error-correcting code. In this paper, we propose the first power side-channel attack on the Key Encapsulation Mechanism (KEM) version of HQC. Our attack utilizes a power side-channel to build an oracle that outputs whether the BCH decoder in HQC’s decryption algorithm corrects an error for a chosen ciphertext. Based on the decoding algorithm applied in HQC, it is shown how to design queries such that the output of the oracle allows to retrieve a large part of the secret key. The remaining part of the key can then be determined by an algorithm based on linear algebra. It is shown in experiments that less than 10000 measurements are sufficient to successfully mount the attack on the HQC reference implementation running on an ARM Cortex-M4 microcontroller.

Original languageEnglish
Title of host publicationSmart Card Research and Advanced Applications - 19th International Conference, CARDIS 2020, Revised Selected Papers
EditorsPierre-Yvan Liardet, Nele Mentens
PublisherSpringer Science and Business Media Deutschland GmbH
Number of pages16
ISBN (Print)9783030684860
StatePublished - 2021
Event19th International Conference on Smart Card Research and Advanced Applications, CARDIS 2020 - Virtual, Online
Duration: 18 Nov 202019 Nov 2020

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume12609 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference19th International Conference on Smart Card Research and Advanced Applications, CARDIS 2020
CityVirtual, Online


  • Error correction
  • HQC
  • Post-Quantum Cryptography
  • Power analysis
  • Side-channel analysis


Dive into the research topics of 'A Power Side-Channel Attack on the CCA2-Secure HQC KEM'. Together they form a unique fingerprint.

Cite this